Fan equipment



Feb. 25, 1964 R WASSON .ETAL 3,122,307

FAN EQUIPMENT 2 Sheets-Sheet 2 Filed Aug. 8. 1961 INVENTORS PUB/5P7 A.W4 550/V SEWELL H. DOW/V5 A Tram/2w United States Patent 3,122,307 FANEQUIPMENT Robert A. Wasson and Sewell H. Downs, Kalamazoo, Mich,assignors to Clarage Fan Company, Kflamazoo, Mich a corporation ofMichigan Filed Aug. 8, 1961, Ser. No. 139,049 7 Claims. (Cl. 230-117)This invention relates in general to a combination fan constructionincluding housing structure having a pair of coaxial, annularpassageways and an impeller assembly including a centrifugal impellerand an axial flow impeller connected to each other and rotatablysupported for effecting the axial flow of gas through the twopassageways simultaneously in opposite axial directions. The use of dualimpellers mounted for simultaneous rotation is very old in the art.However, it is relatively new in the art to use a combinationcentrifugal and axial flow impeller for the purpose of effectingsimultaneous, counteraxial flow of a gas, such as air, through a pair ofradially aligned, annular passageways, particular for the purpose ofexchanging the air within a space with which said passagewayscommunicate. Many attempts, which have been largely unsuccessful, havebeen made to develop a dual fan construction for use in the heating andventilating field. However, there has been little interest in, henceacceptance of, dual fan constructions for this purpose.

It is believed that the lack of widespread acceptance of dual fans hasbeen due largely to the fact that previous dual fan constructions,particularly in the field of ventilation, have used a pair of radiallyaligned and interconnected axial flow fans. It is a well known fact thataxial flow fans, which are economically competitive with a conventionalcentrifugal fan, are incapable of developing total pressures which areoften required in ventilating installations. Moreover, in order to havea comparable capacity, axial flow fans (particularly propeller types)must be operated at tip speeds which create unacceptable noise levels,especially for installations adjoining space occupied by humans. Becauseof their relatively low static pressures, conventional dual propellerunits used for this purpose must be placed close to the air space whichthey are serving, thereby aggravating the noise problems.

The two coaxial passageways, which are required in this type ofstructure, generally have cross-sectional areas which differ verysubstantially. Heretofore, it has been very difficult to develop a dualpropeller fan construction which provides large, balanced flows ofsupply and exhaust air through said passageways without encounteringcostly blade configurations, high impeller velocities (hence noise) and/or high power losses due to turbulence and other obstructions to the airflow. Moreover, even when these problems have been minimized by carefuland costly designing, the dual propeller fan construction has been veryrestricted in its application because of its inability to develop,particularly in the exhaust passageways, the necessary static pressureto utilize ducts in association therewith for more uniform circulation.

In the process of studying these various problems, the applicantsdeveloped a combination impeller construction whereby substantially allof the above discussed problems are materially reduced, if noteliminated, and, more importantly, without creating new problems.

Accordingly, a primary object of this invention has been the provisionof a combination fan construction wherein a centrifugal impeller isconnected to and driven simultaneously with an axial flow fan so that asingle unit having coaxial exhaust and supply passageways can beeffectively and efficiently used without high noisy tip speeds, whichcan be conveniently and acceptably installed adjacent the air scapewhich it serves, which can be manufactured at a cost competitive withdual propeller fan constructions for the same or similar purpose, andwhich is capable of producing more efiicient performance and developinggreater capacities than existing competitive constructions.

A further object of this invention has been the provision of acombination fan construction wherein the supply passageway is on theoutside and a propeller fan is located therein to use the axial flow fanwhere it is most efficient (i.e. of largest diameter) and its relativelysmaller capability for developing static pressure will not adverselyaffect the operation of the unit; and wherein the centrifugal impelleris used in association and communication with the inner and small,exhaust passageway where the higher static pressures are desired.

A further object of this invention has been the provision of acombination fan construction wherein the obstruction of the discharge ofexhaust gases from the centrifugal impeller is reduced to a point farbelow that which is normally encounteded by the discharge of exhause gasfrom an axial flow impeller used under the same circumstances, dueprimarily to the normal char acteristic of the centrifugal impeller todischarge radially; and wherein the capacity of the centrifugal impelleris so much greater than the axial flow impeller normally used in thesame location that the combination fan construction can besatisfactorily used for ventilating not only the air space adjacent theunit but at substantial distances therefrom and connected thereto bysubstantial amounts of duct work.

A further object of this invention has been the provision of acombination fan construction, as aforesaid, which can utilize aconventional centrifugal impeller and a conventional axial flow impellerwith little or no modification or variation required to effect theircombination, and wherein said combined centrifugal and axial flowimpellers can be arranged to provide a high capacity fan constructionwith a minimum of obstructions to the free flow of gas therethrough inboth directions while, at the same time, permitting a housingconstruction which is much smaller than the housing structure requiredfor dual propeller fan constructions capable of performance evenapproaching the performance of the applicants construction.

Other objects and purposes of the invention will become apparent topersons familiar with equipment of this kind after reading the followingdescriptive material and examining the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a combination fan constructionembodying the invention.

FIGURE 2 is a sectional view taken along the line II-II in FIGURE 1.

FIGURE 3 is a broken sectional view substantially as taken along theline lII-III in FIGURE 2.

For convenience in description, the terms upper, lower and words ofsimilar import will have reference to the fan construction as shown inFIGURES 1 and 2 which disclose one normal position of its operation. Theterms inner, outer and derivatives thereof. will have reference to thegeometric center of said fan construction and parts thereof.

General Description The objects and purposes of the invention, includingthose set tfOIllll above, have been met by providing a combination fanconstruction comprised of a housing having wall structure defining innerand outer, substantially coaxial annular passageways and a dual impellerrotatably supported within the housing for effecting simultaneous,counteraxial flow of gas, -such as air, through said passageiways. Thedual impeller is comprised of a centrifugal impeller or wheel which hasan inlet communicating with the inner, annular passageway and anotherimpeller, such as an axial flow fan, located in or adjacent to the outerannular passageway whereby rotation of said dual impeller eifectsexhausting of air through one passageway and supplying of fresh airthrough the other passageway. Sui-table means are provided for effectingrotation of said dual impeller and bathing means is provided forinsuring separation between the ambient source of air supply and theexhaust air. The combination fan of the invention is especially suitedfor mounting upon a horizontal wall, such as a roof, for exchanging thegas, such as air, in the space below said wall or roof including spaceconnected to said fan unit by ducts and disposed at substantialdistances from the space directly below the unit. However, saidcombination fan construction can also be mounted with equalefiectiveness upon a substantially vertical wall for the same or similarpurposes.

Derailed Construction The combination fan construction 14} (FIGURES 1and 2), which illustrates a preferred embodiment of the inventiondesigned for roof mounting is comprised of an impeller housing 11 inwhich a dual impeller 12 is rotatably supported and rotated by a drivemechanism including at least a motor 13, which may drive the impellerthrough coupling means, such as the belt arrangement shown in FIGURE 2.The motor 13 may be supported upon the housing 11 within a motor cover14. The housing 11 may be supported upon a base 16 which is in turnmounted, for example upon the roof 17 above the space being serviced bythe fan construction 10.

The base 16 is preferably, but not necessarily, a \substantially flatand rectangular structure having a horizontal top wall .18 and asubstantially vertical flange 19 extending partially or completelyaround and downwardly from the perimeter of the top wall 18. Additional,intermediate support elements, suoh as that indicated at 22 in FIGURE 2,may be provided between the roof 17 and top wall 18 for supportingpurposes, if necessary. The top wall 18 has a central opening 23 and maybe provided with an integral circular fiange 24 around said opening forreasons appearing hereinafter.

The base 16, the impeller housing :11, the dual impeller 12 and many ofthe parts associated therewith are preferably, but not necessarily,fabricated from relatively still" and durable material such as sheetmetal, bar stock, metal castings and the like.

The impeller housing 11 (FIGURE 2) includes an outer cylindrical casing26, the lowerend of which is snugly sleeved around and secured as bywelding to the flange 24. Where, as in this embodiment, the fanconstruction 10 is disclosed as a roof mounted ventilator, thecylindrical casing 26 is axially upright and open at its upper and lowerends. An inner cylindrical wall me ber 27 is concentrically disposedwithin and supported upon the casing 26 by the plates or brackets 28.The outer casing 26 and cylindrical wall member 27 define between theman outer, annular passageway 29 which communicates between the upper endof the casing 26 and the central opening 23 in the base 16.

The roof 17 (FIGURE 2) is preferably provided with a circular opening3-2 which is preferably coaxial with and slightly larger than thecentral opening 23 in the top wall 18. A cylindrical sleeve or duct 33may be snugly disposed within the circular roof opening 32 so that itextends toward and adjacent the top wall 18. Means, such as acylindrical duct 34, may be sleeved upon the lower end of the wallmember 27 in a conventional manner for communicating between the lowerend of the wall member 27 and a selected air space within the zone belowthe roof 17. Thus, the two cylindrical ducts 33 and 34 define, ineffect, a continuation of the outer, annular passageway 29.

The bearing assembly 36 includes a pair of axially spaced, coaxialbearings 37 and 38, which are supported upon and within the oppositeends of cylindrical tube 39. Said tube 39 is supported coaxially withinand upon the cylindrical wall member 27 by support brackets 42 which aresecured to and extend between the tube 39 and wml member 27. The upperend of the bearing assembly 36 extends substantially above the upper endoi the wall member 27 for rotatably supporting an impeller shaft 43coaxially within the wall member 27. The wall member 27 and the lowerend of the tube 39 define between them an inner annular passageway 44which communicates at its lower end with the cylindrical duct 34.

(The dual impeller 12 (FIGURE 2) includes a centrifugal fan wheel 46which may be of any convenient type. in this particular embodiment, andfor illustrative purposes only, said wheel 46 is comprised of a backplate 47 supported upon and secured to a hub 48 which is mounted uponthe shaft 43 above the bearing assembly 36 and secured to said shaft bymeans including a set screw 49. The wheel 46 has a plurality of blades52 secured at one end of each to said back plate 47 and at the other endof each to a rim 53, which defines a wheel inlet opening 54. Means, suchas a pair of set collars 56 and 57, are secured to the shaft 43 adjacentthe upper and lower ends, respectively, of the bearing assembly 36 toprevent axial movement of the shaft 43 with respect to said hearingassembly. 7

A conical ring 53 is coaxially secured, as by welding, to the lower sideof the rim 53 adjacent to the periphery thereof so that said ring 58converges downwardly and has an inside diameter about equal to theinside diameter of the rim 53. A cylindrical sleeve or inlet pipe 61 iscoaxially secured, as by welding, to the lower edge of the conical ring58 and extends downwardly therefrom toward and adjacent the upper end oithe wall member 27. In this particular embodiment, the sleeve 61 issomewhat smaller diameter than the cylindrical wall member 27. However,this specific arrangement may be varied depending upon the specificdetails of construction required by the particular installation.Moreover, it will be apparent that the rim 53 may, under somecircumstances, be omitted by extending the lower ends of the blades 52downwardly so that they are secured to the ring 58 or alternatively,that the conical ring SSmay be omitted under some circumstances byextending the sleeve 61 up to the rim.

The dual impeller 12 also includes an outer impeller 62 (FIGURE 3) whichmay be or" a substantially conventional type, such as an axial flow fan.In this particular embodiment, the fan 62 is comprised of an annularsupport member 63 which snugly and concentrically embraces and issecured, as by welding, to the lower end of the sleeve 61 adjacent theupper end of the wall member 27. The outside diameter of the annularsupport member 63 is approximately equal to the outside diameter of saidwall member 27. A plurality of propeller blades 64 are secured, as bythe rivets 66, to the peripheral surf face of the support member 63 atuniform intervals there-.

around so that said blades extend radially toward and adjacent the outercasing 26, preferably adjacent the upper ends thereof.

The blades of the outer impeller 62 (FIGURES 2 and 3) are arranged sothat rotation of the dual impeller.

12, which efiects the proper radial discharge from the centrifugal Wheel46, will also cause the outer impeller 62 to move air or gas downwardlythrough the outer annular passageway 29 while gas is being movedupwardly through the inner annular passageway 44 by the centrifugalwheel 46.

A pair of spaced supports 67 (FIGURE 2) for the motor mounting bracket68 may in this embodiment, be mounted upon the casing 26 and extend insubstantially the same direction therefrom. The motor 13 may be mountedin a conventional manner, as by means of the bolts 69, upon an uprightflange 72 of the mounting bracket 68 so that the motor shaft 73 extendsvertically upwardly from the motor 13. The motor cover 14 is mountedupon the supports 67 and/ or the casing 26 adjacent thereto. Although aparticular motor mounting means is shown and described in thisembodiment it should be recognized that, under some circumstances, themotor may be mounted coaxially above or below the shaft 43 and connecteddirectly thereto.

An annular bafiie assembly 74 is spaced upwardly from the upper end ofthe outer casing 26 and is supported by a plurality of upright supportbars 76 which in this embodiment are secured to and connected betweenthe upper end of the outer casing 26 and a portion of said baflle memberdirectly thereabove. The baflle assembly '74 includes a lower bafllering 75 which is mounted near its inner radial edges upon the supportbars 76. The radially outer portion of the battle ring 75 curves fromsaid support bars 76 downwardly and outwardly to terminate in asubstantially vertical flange 77 which preferably telescopes slightlyand is spaced radially outwardly from the upper end of the outer casing26. As shown in FIGURE 3, a portion of the batlle assembly 74 is omittedin the region of the motor cover 14 to mount said cover adjacent heouter casing 26. The baflie ring 75 cooperates with the upper end of thecasing 26 to define an inlet passage 78 which communicates between asupply of ambient air and the upper end of the outer annular passageway29 The bafile assembly 74 includes a deflector ring 84 which isconcentrically supported upon and secured to the baffle ring 75. Thering 84 has a radially inward por tion 85 curving upwardly and inwardlyto meet the periphery of the rim 53. The deflector ring 84 also has aperipheral portion 86 which curves upwardly and outwardly.

The impeller housing 11 includes an inverted, dishshaped cover member 81which is supported coaxially upon and spaced upwardly from the annularbaflle assembly 74 by the support bars 82 which are secured thereto andextend there-between. The diameter of the cover member 81 in thiembodiment is substantially greater than the diameter of the centrifugalwheel 46, which it covers, and is slightly less than the diameter of thebaffle member 74. In this arrangement with the shaft 43 being drivenfrom above, the cover member 81 has a central opening 83 through whichthat portion of the hub 43 containing the set screw 49 extends so thatsaid set screw is accessible. The diameter of the deflector ring 84 ispreferably slightly greater than the diameter of the cover member 81 sothat air discharged between the deflector ring 84 and the cover member81 by the centrifugal wheel 46 is deflected upwardly away from thesupply of ambient air received into the inlet passage 78.

A driven pulley 87 may be mounted upon the upper end of the shaft 43adjacent the hub 48 and secured thereto by means including the set screw88. -A driving pulley 91 is mounted upon the motor shaft 73 by meansincluding the set screw 92. The pulleys 87 and 91 are interconnected byone or more belts 93, whereby rotation of the motor shaft 73 effectsrotation of the dual impeller 12.

Operation Although the operation of the combination fan construction It}is probably evident from a reading of the above description thereof,such operation will now be reviewed briefly. With the fan constructionIt) installed on a roof 17, for example, the cylindrical wall member 27will normally be connected to some form of duct 34 which willcommunicate with the space from which gas or air is to be exhausted.Also, the cylindrical wall member 26 may be extended by connection tosome form of duct 33 in such a way as to move the air passing downwardlytherethrough into zones spaced a substantial distance from the fanconstruction 10.

By energizing the motor 13, the impeller 12 is caused to rotate in adirection whereby gas or air is caused to move upwardly through theinner annular passageway 44 within the wall member 27 and sleeve 61toward and through the inlet Opening 54 in the centrifugal wheel 46 andis then discharged in a substantially conventional manner radiallyoutwardly by the blades 52 of the wheel 46, so that it discharge betweenand radially beyond the cover member 81 and deflector ring 84. As statedabove, the deflector ring 84 causes the discharged air to be deflectedaway from the inlet passage 78 which deflection will usually beaugmented by the normal convection currents in the ambient air. Theouter impeller 62 will, at the same time, draw air through the inletpassage 78 and move it downwardly through the outer annular passageway29 into whatever zone or air space may be in communication with the duct33. A sidewardly opening baffle ring, indicated by broken lines at 94 inFIGURE 2, may be provided for deflecting the air moving through theouter passageway 29 sidewardly away from the air entering the innerannular passage. Although the drawings and much of the discussiondisclose operation of the fan construction It) above a roof, a reversedinstallation is fully contemplated, in which the entire construction isinverted and suspended from the under side of a roof so that the inletand exhaust functions of the outer and inner impellers would beexchanged. In such an installation appropriate baffles and ducts wouldbe provided.

It is common knowledge that the most eflicient portion of a propellertype or axial flow fan is in the region thereof spaced a substantialdistance from the hub, and preferably including that portion thereofnear the periphery of the propeller fan. Accordingly, the impeller 12has been designed, with this fact in mind, so that the propeller fan islocated in the outer one of the two annular passageways. =It is alsovery well known that a centrifugal fan can operate substantially at fullcapacity and at peak performance where the inlet duct communicating withthe inlet of the fan has a diameter about equal to the opening in theinlet side of the wheel. Thus, instead of using a low etiiciency, lowpressure type of propeller or axial flow fan in the inner passageway 44.Applicant has arranged to use a relatively high eificiency and highpressure, centrifugal Wheel, which greatly enhances the performance ofthe fan construction while maintaining an overall size, capacity andcost which are entirely competitive with existing dual fanconstructions, utilizing two propeller fans.

It will also be seen that, where the :fan construction 1%? is used in aclosed system, any tendency for the propeller fan portion of theimpeller 12 to be unable to meet the full requirements for a supply ofair will be overcome by a negative pressure condition created in thesystorn by the centrifugal fan wheel which will actually induce the flowof air through the outer annular passageway 29 and thereby augment theoperation of the propeller fan portion of the impeller.

it has been found that, by controlling the diameters of the annularmember 63, the sleeve 61 and the adjacent end portion of the wall member27, the leakage of air or gas between the annular member 63 and the wallmember 27 can be carefully controlled. This condition is aided by thefact that the space between the members 27 and 63 is downstream of thepropeller fan and upstream of the centrifugal fan. Where contaminationof the supply air by the exhaust air within the fan construction 10 isundesirable, the diameter of the member 63 is very slightly larger thanthe diameter of the member 27 in this particular embodiment. As aresult, a small amount of air leaks between the members 27 and 63 fromthe outer passageway 28 into the inner passageway 44.

Accordingly, the combination fan construction 10 of this invention isnot merely another dual fan construction having limited utility andrestricted primarily to use for exchanging gas in, or ventilating, thezone immediately adjacent the wall upon which the fan construction ismounted. Applicants fan construction 10 is, on the contrary, capable ofa wide variety of uses wherein separate exhaust and supply units of thecentrifugal type are presently used in order to provide both thecapacity and static pressures which are required, particularly where itis important to hold down the noise which is normally incident to theuse of strictly propeller type fan assemblies for this purpose.

In this regard, it will be observed that a typical, slow speedmultiblade centrifugal fan wheel will normally be used in the fanconstruction It) where a ventilating application is involved.Accordingly, the propeller fan which provides the supply air will alsobe operating at a relative ly low tip speed which will not produce anobjectionable noise. Moreover, since the propeller fan is shrouded bythe casing 26, such noise will also be reduced somewhat. Since the mostefficient outer portion of the propeller fan is being used in theimpeller 12, adequate air movement will normally be provided asdiscussed above.

Although a particular preferred embodiment of the invention has beendisclosed above in detail for illustrative purposes, it will beunderstood that variations or modifications of such disclosure, whichcome within the scope of the appended claims, are fully contemplated.

What is claimed is:

l. A gas moving apparatus, comprising:

an outer casing of sheet material and circular cross section;

an inner, cylindrical wall member of sheet material and coaxiallydisposed within and radially spaced from said casing;

means rigidly securing said wall member with respect to said casing;

a shaft, and bearing means mounted upon said wall member and rotatablysupporting said shaft coaxially within said wall member, said shaftextending axially beyond one end of said wall member;

a centrifugal impeller concentrically supported upon said shaftexternally of and axially spaced from said wall member and having aninlet side opposing and axially spaced from said one end of said wallmemher;

a sleeve member coaxially encircling and spaced radially from said shaftand bearing means, said sleeve member being secured at one axial endthereof upon the inlet side of said impeller and extending toward andadjacent said one end of said wall member, said sleeve member and saidwall member defining therewit'nin an annular inner passageway encirclingsaid shaft and bearing means, said sleeve member and said wall memberdefining with said casing an annular outer passageway, rotation of saidcentrifugal impeller eifecting movement of gas axially along said innerpassageway toward said inlet side of said centrifugal impeller andthence radially therefrom:

a plurality of axial flow blades rigidly secured upon said sleeve memberat intervals around the sleeve member adjacent said wall member, saidblades being spaced axially from said impeller and being arranged insaid outer passageway to effect the flow of gas therealong axially awayfrom said centrifugal impeller;

drive means for rotating said impeller and said blades around the axisof said shaft; and

annular bafile means supported upon said casing and encircling saidsleeve member adjacent said impeller to direct the gas discharged bysaid impeller away from the gas drawn by said blades into said outerpassageway.

2. The structure of claim 1 including a base member supporting saidcasing, racket means supporting said drive means upon said casing,coupling means connecting said drive means to said shaft for rotationthereof, and a cover member extending over said impeller and supportedupon said casing, said cover member being spaced from said bafiie means.

3. The structure of claim 1 wherein the total pressure developed by thecentrifugal impeller within the inner passageway adjacent the said oneend of said wall member is lower than the total pressure developed bythe said blades in the outer passageway adjacent the said one end ofsaid wall member when said impeller and said blades are rotatingnormally, so that gas is moved from said outer passageway into saidinner passageway between said sleeve and said wall member.

4. The structure of claim 1 wherein the relative locations and diametersof the adjacent end portions of said sleeve and said wall member aresuch that a predetermined amount of gas moves between said sleeve andsaid Wall member in a selected radial direction.

5. A gas moving apparatus, comprising:

an outer casing having a portion of substantially circular crosssection;

a centrifugal impeller having an inlet side;

shaft and bearing means secured with respect to said casing androtatably supporting said impeller so that said impeller issubstantially coaxial with, external of, and axially spaced from one endof said portion of circular cross section, said impeller having itsinlet side opposing said end of said portion and spaced from said end ofsaid portion;

a sleeve substantially coaxial with, and secured near one end thereofto, the inlet side of said impeller, said sleeve extending from saidimpeller toward said casing and being coaxial with said shaft andbearing means, said sleeve defining therewithin an inner passageway, andsaid sleeve and said casing defining therebetween an outer passageway,rotation of said centrifugal impeller around the axis of said shafteifecting movement of gas axially along said inner passageway towardsaid impeller and radially away from said impeller; and

a plurality of axial flow blades mounted upon said sleeve at intervalsaround the periphery thereof and spaced axially from said impeller, saidblades being arranged within said outer passageway so that said rotationof said impeller causes said blades to efiect movement of gas axiallyalong said outer passageway.

6. The structure according to claim 5 including baffle means connectedto said casing and substantially encircling said sleeve adjacent saidimpeller to direct the gas discharged by said impeller away from theadjacent portion of said outer passageway.

7. The structure according to claim 6 wherein said sleeve extendscoaxially into the adjacent end of said casing.

References Cited in the file of this patent UNITED STATES PATENTS2,152,614 Younger Mar. 28, 1939 2,189,008 Kurth Feb. 6, 1940 2,622,858Hughes Dec. 23, 1952 2,827,261 Parker t t. l Mar. 18, 1958

1. A GAS MOVING APPARATUS, COMPRISING: AN OUTER CASING OF SHEET MATERIALAND CIRCULAR CROSS SECTION; AN INNER, CYLINDRICAL WALL MEMBER OF SHEETMATERIAL AND COAXIALLY DISPOSED WITHIN AND RADIALLY SPACED FROM SAIDCASING; MEANS RIGIDLY SECURING SAID WALL MEMBER WITH RESPECT TO SAIDCASING; A SHAFT, AND BEARING MEANS MOUNTED UPON SAID WALL MEMBER ANDROTATABLY SUPPORTING SAID SHAFT COAXIALLY WITHIN SAID WALL MEMBER, SAIDSHAFT EXTENDING AXIALLY BEYOND ONE END OF SAID WALL MEMBER; ACENTRIFUGAL IMPELLER CONCENTRICALLY SUPPORTED UPON SAID SHAFT EXTERNALLYOF AND AXIALLY SPACED FROM SAID WALL MEMBER AND HAVING AN INLET SIDEOPPOSING AND AXIALLY SPACED FROM SAID ONE END OF SAID WALL MEMBER;